Valve



Aug. 23, 1966 o. L. RICE 3,267,961

VALVE Filed April 16, 1964 2 Sheets-Sheet 1 L N R ORVAL L. RICE I I5 iBY ATTORNEYS INVENTOR 0. L. RICE Aug. 23, 1966 VALVE 2 Sheets-Sheet 2Filed April 16. 1964 FIG .2

INVENTOR ORVAL L. RICE PUMP ATTORNEYS;

United States Patent 3,267,961 VALVE Orval L. Rice, Kalamazoo, Mich,assignor to The New York Air Brake Company, a corporation of New JerseyFiled Apr. 16, 1964, Ser. No. 360,294 3 Claims. (Cl. 137596) Thisinvention relates to valves for hydraulic systems used to actuatedouble-acting, differential are-a piston motors.

In systems of this kind, the piston motor is controlled by amulti-position directional control valve having an inlet port connectedwith a pump, an exhaust port connected with a reservoir or tank, and apair of motor ports which are connected with the opposite sides of thepiston motor. The directional control valve has at least a neutral orhold position in which each motor port is isolated from the other threeports, a raise portion in which one motor port is connected with theinlet port and the other motor port is connected with the exhaust port,and a lower position in which the connections between the motor portsand the inlet and exhaust ports are reversed. The valve may also have afloat position in which all four ports are interconnected.

These systems are used frequently on loaders and bulldozers to controlthe hoist motors which raise and lower the bucket and blade,respectively, and one of the problems encountered in this service isthat of maintaining the expanding side of the piston motorliquid-filled, and thus avoiding cavitation, during implement droppingoperations without retarding unduly the rate of movement. One solutionto this problem is disclosed in US. Patent 3,049,101, granted August 14,1962, and includes a bypass valve which is mounted on or near the pistonmotor and which is triggered to open and interconnect the contractingand expandingsides of the motor when the directional control valve isshifted to float position. While this scheme affords the desired resultsin cases where the directional control valve is shifted to floatposition to effect dropping of the implement, it affords littleprotection against cavitation in cases where the implement is dropped asa result of shifting the directional control valve to the lowerposition. Furthermore, the valving device disclosed in that patent isnot suitable for use in installations wherein quick dropping of theimplement is required when the directional control valve is in the lowerposition.

The object of this invention is to provide an improved version of thevalving device disclosed in the patent mentioned above which allowsby-passing of oil from the contracting to the expanding side of themotor in either the lower or the float position of the directionalcontrol valve, and which, in the latter case, also affordsanti-cavitation flow control action when the directional control valveis in the lower position.

The preferred embodiment of the invention is described herein withreference to the accompanying drawings in which:

FIG. 1 is a diagram, partly in schematic form, showing the automaticversion of the improved valving device and a typical circuit with whichit is used.

FIG. 2 is a diagram, also partly in schematic form, showing thetriggered version of the improved valving device and a typical circuitwith which it is used.

As shown in FIG. 1, the improved valving device 11 is incorporated in acircuit for actuating a double-acting piston motor 12 which is arrangedto raise and lower the blade 13 of a bulldozer. The circuit includes athreeposition, sliding plunger, directional control valve 14 having aninlet port connected with pump 15, an exhaust port connected with tank16, and a pair of motor ports 17 and 18. The letters N, R and L indicatethe neutral,

Patented August 23, 1966 raise and lower positions, respectively, ofvalve 14.

Valving device 11 includes a housing containing a pair of parallelthrough bores 19 and 21 and four ports 22-25; the ports 22 and 23 beingconnected with the motor ports 17 and 18, respectively, of valve 14 byconduits 26 and 27, and the ports 24 and 25 being connected with thehead and rods ends, respectively, of motor 12 by conduits 28 and 29. Acored passage 31, having portions 31a and 31!) which encircle bores 19and 21, respectively, establishes continuous communication between ports23 and 25, whereas cored passages 32 and 33 connect ports 22 and 24 withthe longitudinally spaced annular chambers 32a and 33a, respectively,encircling bore 19. As in the case of cored passage 31, cored passage 33has a portion 33b which encircles bore 21.

The opposite ends of valve bore 19 are closed and sealed by plugs 34 and35, and the bore contains a sliding valve plunger 36 formed with anannular groove 37 which defines two valve lands 38 and 39. The left endof plunger 36 is enclosed by a chamber 41 which communicates with coredpassage 32 through the restricted passage 42 extending through plug 43.The combined forces developed by the pressure in this chamber 41 and thecoil compression spring 44 biases valve plunger 36 to the right to aposition in which the plunger engages plug 35 and land 38 isolateschambers 32a and 33a from each other. The plunger 36 is shifted in theopposite direction by the pressure in cored passage 31 which acts uponits right end 45, and, as the plunger moves to the left, the throttlingnotches 46 formed in the right edge of land 38 progressively opencommunication between annular chambers 32a and 330:. When the plungerreaches its extreme leftward position wherein its left end abuts plug34, annular groove 37 spans chambers 32a and 33a and establishes asubstantially unrestricted flow path between them. Land 39 isolatesannular chamber 32a from cored passage 31 in all positions of the valveplunger 36.

Valve plunger 36 contains an ,axial bore 47 Whose left end is closed andsealed by plug 48 and which is intersected by two sets oflongitudinal-1y spaced radial passages 49 and 51 which register withannular chambers 32a and 33a, respectively, when the valve plunger is inthe illustrated position. Flow through axial bore 47 is controlled by acheck valve 52 which is biased closed by a coil compression spring 53and by the pressure in the chamber 54 at its left end. Chamber 54 isconnected with cored passage 33 by the axial and radial passages 55 and56, respectively, in check valve 52 and by the radial passages 51 invalve plunger 36.

Valve bore 21, whose opposite ends are closed and sealed by plugs 57 and58, contains a check valve 59 and a by-pass valve 61 which controlcommunication between the central bore portion 62 and the cored passages31 and 33, respectively. Check valve 59 is biased closed by a coilcompression spring 63 and by the pressure in chamber 64 whichcommunicates with cored passage 31 through the axial and radial passages65 and 66, respectively, formed in the valve. This valve is opened bythe pressure in bore portion 62 which acts upon its nose 67. By-passvalve 61, on the other hand, is biased closed by a coil compressionspring 68 and by the pressure in chamber 69, and is urged in the openingdirection by the pressure in cored passage 33 which acts upon an annularreaction surface 71 at its right end which is bounded by its seat 72 andits outer periphery. Chamber 69 communicates with cored passage 33through the axial and restricted radial passages 73 and 74,respectively, in valve 61, and with the chamber 41 through the passagein the valve housing. The flow restriction afforded by passage 74 isgreater than that afforded by the passage 42 in plug 43. As will beapparent from the following description of operation, by-pass valve 61opens automatically when the rate of flow of the fluid from port 24 toport 22 through the pilot path including chambers 41 and 69 reaches apredetermined value.

When directional control valve 14 is in its neutral position, each ofthe motor ports 17 and 18 is isolated from the other and from both thepump and the tank 16. At this time, the components of valve 11 assumetheir illustrated positions and motor 12 is hydraulically locked. Sincevalve 14 usually is of the open center type, it establishes anunrestricted unloading path from pump 15 to tank 16. In order to raiseblade 13, the operator shifts directional control valve 14 to its raiseposition in which the open center unloading path is closed and motorports 17 and 18 are connected with pump 15 and tank 16, respectively.The fluid delivered to valve 14 by pump 15 now flows to the head end ofmotor 12 via motor port 17, conduit 26, port 22, cored passage 32,annular chamber 32a, radial passages 49, axial bore 47, check valve 52,radial passages 51, cored passage 33, port 24 and conduit 28.Simultaneously, the rod end of motor 12 is vented to tank 16 through apath including conduit 29, port 25, cored passage 31, port 23, conduit27 and motor port 18. Since the head and rod ends of motor 12 are nowpressurized and vented, respectively, the motor lifts blade 13. Duringthis operation, the valves 36, 59 and 61 in valving device 11 remain intheir illustrated positions. When the blade 13 reaches the desiredelevation, the operator returns directional control 14 to its neutralposition and thereby interrupts the supply and vent paths and againhydraulically locks motor 12. Check valve 52 in valving device 11 nowcloses.

Lowering of blade -13 is effected by shifting directional control valve14 to its lower position in which the open center unloading path isclosed and motor ports 17 and 18 are connected with tank 16 and pump 15,respectively. Now the fluid delivered by pump 15 is transferred to therod end of motor 12 through a supply path including motor port 18,conduit 27, port 23, cored passage 31, port 25 and conduit 29. Sinceconduit 26, port 22 and cored passage 32 are now connected with tank 16through the directional control valve, the pressure in chamber 41decreases. As a result, the supply pressure in cored passage 31, whichacts upon the right end 45 of valve plunger 36, shifts the valve plunger36 to the left and causes throttling notches 46 to open communicationbetween annular chambers 32a and 33a. Oil displaced from the head end ofmotor 12 now may flow to tank 16 along a path including conduit 28, port24, cored pas sage 33, annular chamber 33a, throttling notches 46,annular chamber 32a, cored passage 32, port 22, conduit 26 and motorport 17. Therefore, motor 12 commences to lower blade 13.

Oil displaced from the head end of motor 12 also can flow to tank 16along a second vent path including restricted passage 74, axial passage73, chamber 69, passage 75, chamber 41 and restricted passage 42. Theoil flowing along this pilot path experiences a drop in pressure as itpasses through restricted passage 74 and this pressure drop increases asthe rate of flow increases. When the flow rate reaches a predeterminedvalue, the pressure differential between cored passage 33 and chamber 69develops a force on by-pass valve 61 which overcomes the bias of spring68 and causes that valve to open. When this happens, some of the oilreturning from the head end of motor 12 is diverted to the rod endthrough bore portion 62, check valve 59, cored passage 31, port 25 andconduit 29. The fluid transferred from the contracting to the expandingend of motor 12 through this by-pass path maintains the rod end of motor12 liquidfilled, and, since the length of this transfer path isrelatively short, it imposes little flow resistance. As a result, blade13 can drop rapidly without risk of cavitation. The amount of oil whichfollows the by-pass path depends upon the capacity of pump 15 and themagnitude of the load exerted on motor 12 by blade 13. If the load islarge and motor 12 tends to move at a rate considerably greater thanthat with which the pump can keep pace, the pressure in cored passage 31will decrease and plunger valve 36 will shift to the right and causenotches 46 to throttle further the return flow to the directionalcontrol valve 14. This increases the pressure in cored passage 33 andcauses by-pass valve 61 to open further. As a result, a greater portionof the oil displaced from the head end of motor 12 will be diverted tothe rod end through the by-pass path defined by bore portion 62. On theother hand, under reduced load conditions, the pressure in cored passage31 will rise and cause valve plunger 36 to move to the left and reducethe throttling effect at notches 46. In this case, by-pass valve 61moves in the closing direction and causes less fluid to be transferredto the rod end of motor 12 through the by-pass path. It is thus apparentthat the valves 36 and 61 act together to split the return flow frommotor 12 so that the expanding side of motor 12 always receivessufficient oil to prevent cavitation. Since the effective area of thehead end of motor 12 is greater than the effective area of the rod end,the quantity of oil being returned to valving device 11 is alwaysgreater than that demanded by the rod end. Consequently, some oil alwaysreturns to tank 16 through the plunger valve 36.

It should be noted here that the lower position of directional controlvalve 14 is also used during digging operations. In this case, the blade13 encounters considerable resistance to movement so the pressure in therod end of motor 12 and in cored passage 31 is high. Therefore, valveplunger 36 assume-s its leftmost position, in which it opens fully thereturn path to valve 14, and the .by-pass valve 61 and check valve 59close. Under this condition, maximum system pressure is available toforce the blade 13 into the ground.

It might be mentioned here that since the chamber 41 at the left end ofvalve plunger 36 is in communication with the other fluid-containingspaces of valving device 11 only through restricted passages 42 and 74,this chamber and the left end of valve plunger 36 form a dashpot. Theprovision of this dashpot tends to stabilize the action of valve 36 andthus minimize valve chatter.

-In the FIG. 2 embodiment, the improved valving device 11 isincorporated in a circuit including a four-position directional controlvalve 14 having a float position, and wherein the double-acting motor12' is so arranged that its rod end is contracted by the load exerted byblade 13'. Valvin-g device 1 1' is identical to its counterpart in FIG.1 except that the chamber 69 behind the :by-pass valve 61 is isolatedfrom the chamber 41' at the left end of plunger valve 36' and isprovided with an outlet connection in the form of a tapped port formedin plug 57'. In this embodiment, the bypass action of valve 61 does nottake place automatically upon the occurrence of a predetermined flowrate, but is triggered manually by shifting the directional controlvalve to a selected position, in this case the float position. This isaccomplished by providing in the directional control valve 14 a ventvalve 76 .which includes an annular chamber 77 that is connected withport 7 5' by a conduit 78 and an annular exhaust chamber 79 whichcommunicates with tank 16. The plunger 14a of valve 14 norm-allyisolates chamber 77 from exhaust chamber 79, but is provided with anannular groove 81 that spans these chambers, and thus vents chamber 69',when it is shifted to the float position.

When the directional control valve 14 of FIG. 2 is shifted to its lowerposition and pump 15 and tank 16 are connected with conduits 27' and 26,respectively, oil is delivered to the head end of motor 12' through asupply path including port 23', cored passage 31', port 25 and conduit29'. The pressure in this path acts upon the right end 45 of plungervalve 36 and develops a force which shifts it to the left and causesthrottling notches 46 to interconnect annular chambers 32a and 33a. Oildisplaced fromthe rod end of motor 12' may now flo'w to tank 16 along avent path including conduit 28', port 24', cored passage 33', annularchamber 33a, throttling notches 46f, annular chamber 32a, cored passage32, port 22' and conduit 26'. Since vent valve 76 is closed, by-passvalve 61 remains in its illustrated closed position and preventstransfer of fluid from the contracting to the expanding side of motor12. However, since plunger valve 36' is responsive to the pressure inthe cored passage 31 and varies the restriction afforded by notches 46'in inverse relation to that pressure, the valving device 11 doesmaintain a positive pressure in the supply path leading to the expandingside of motor 12 and insures that motor 12 moves at a rate that does notexceed the capability of pump 15'. Thus, while the rate of movement ofmotor 12' in the lower position of valve 14' is less than the rate ofmovement of motor 12 in the lower poist-ion of valve 14, protectionagainst cavitation is provided.

Quick dropping of the blade 13 in FIG. 2 is effected by shiftingdirectional control valve 114' to its float position in which motorports 17' and 18' are connected with each other and with both the pump15 and the tank 16'. At this time, plunge-r groove 81 spans annularchambers 77 and 79 and opens a pilot path from chamber 69 to tank 16'. Asmall portion of the oil expelled from the rod end of motor 12 now flowsthrough this pilot path and creates a pressure differential betweencored passage 33' and chamber 69' which causes by-pass valve 61' to openagainst the opposing bias of spring 68. As a result, oil may now flowdirectly from the contracting to the expanding side of motor 12 throughthe bypass path defined by bore portion 62'. Because of the areadifferential between the rod .and head ends of motor 12, and the factthat pump 15' is unloaded in the float position of valve 14', all of theoil displaced from the rod end of motor .12, except that small portionflowing through the pilot path controlled by vent valve 76, may berequired .to maintain the head end of motor 12 liquidfilled. Thus, it ispossible that plunger valve 36' will assume a position in which land 38'interrupts flow to port 22. However, in the usual case, the backpressure imposed on pump 15 by the unloading path in valve 14' is highenough to cause a substantial part of the oil delivered by the pump toflow to motor 12. Therefore, in the normal case, the return fiow fromthe contracting side of motor 12' is split in the same way as in thebypassing operation of FIG. 1. In any event, valving device 1-1 permitsmotor 12 to move rapidly without risk of cavitation.

When directional control valve 14' is in its neutral position, the partsof valving device 11' assume their illustrated positions. Since chamber69' is not connected with chamber 41', the load pressure in port 24 isnot transmitted to port 22'. Therefore, unlike the valving device 11 ofFIG. 1, valving device 11 afiords load drop protection and eliminatesthe need for a load drop check valve in directional control valve 14'.Thus, should supply pressure decrease, as a result, for example, of pumpfailure, when directional con-trol valve 14 is in its raise position,check valve 52' will close the only path between ports 22 and 24 andprevent downward drifting of motor 12.

As stated previously, the drawings and description relate to thepreferred embodiments of the invention. Since changes can be made inthese embodiments without departing from the inventive concept, thefollowing claims should provide the sole measure of the scope of theinvention.

What I claim is:

1. A valve comprising (a) a housing containing four ports;

(b) a valve bore intersected by two longitudinally spaced passages,there being a first passage which communicates with the first port and asecond passage which communicates with the second port;

(0) a third passage interconnecting the third and fourth ports;

(d) a flow control valve reciprocable in the bore between first andsecond positions in which it closes and opens, respectively,communication between the first and second passages through the valvebore, the flow control valve carrying means which cooperates with thewall of the bore to throttle progressively said communication as thevalve moves toward the first position;

(e) spring means biasing the flow control valve toward the firstposition;

(f) means defining a damping chamber in restricted communication withthe second passage and enclosing one end of the flow control valve;

(g) means at the other end of the fiow control valve responsive to thepressure in the third passage for urging the flow control valve towardthe second position;

(h) an internal passage in the fiow control valve intersected by firstand second longitudinally spaced transverse passages that open throughthe outer periphery of the flow control valve and register with thefirst and second passages, respectively, when the flow control valve isin the first position;

(i) a first check valve located in the internal passage and arranged toprevent flow from the first transverse passage to the second transversepassage through the internal passage but to permit flow in the reversedirection;

(j) biasing means, including means responsive to the pressure in thefirst passage and a spring, urging the first check valve closed;

(k) a by-pass passage interconnecting the first and third passages;

v (l) a second check valve arranged to prevent flow from the thirdpassage to the by-pass passage but to permit flow in the reversedirection;

(m) a control chamber having a restricted inlet connection leading tothe first passage and an outlet connection;

(11) a by-pass valve controlling communication between the first passageand the bypass passage;

(0) spring means biasing the bypass valve closed; and

(p) means responsive to the pressure differential between the firstpassage and the control chamber for moving the by-pass valve in theopening direction.

2. A valve as defined in claim 1 wherein the outlet connection for thecontrol chamber leads to said damping chamber; and the restricted inletconnection of the control chamber afiiords a higher degree of flowrestriction than the restricted connection between said damping chamberand the second passage.

3. In combination (a) a valve as defined in claim 1; and

(b) a vent valve connected with the outlet connection of the controlchamber and operable selectively to open and close this outletconnection.

References Cited by the Examiner UNITED STATES PATENTS 2,367,682 1/1945Kehle 91-436 2,607,599 8/1952 Kanuch l37596.l2 2,704,087 3/1955 Lindsay91-447 3,049,101 8/1962 Ruhl 91-420 M. CARY NELSON, Primary Examiner.

HENRY T. KLINKSIEK, Assistant Examiner.

1. A VALVE COMPRISING (A) A HOUSING CONTAINING FOUR PORTS; (B) A VALVEBORE INTERSECTED BY TWO LONGITUDINALLY SPACED PASSAGES, THERE BEING AFIRST PASSAGE WHICH COMMUNICATES WITH THE FIRST PORT AND A SECONDPASSAGE WHICH COMMUNICATES WITH THE SECOND PORT; (C) A THIRD PASSAGEINTERCONNECTING THE THIRD AND FOURTH PORTS; (D) A FLOW CONTROL VALVERECIPROCABLE IN THE BORE BETWEEN FIRST AND SECOND POSITIONS IN WHICH ITCLOSES AND OPENS, RESPECTIVELY, COMMUNICATION BETWEEN THE FIRST ANDSECOND PASSAGES THROUGH THE VALVE BORE, THE FLOW CONTROL VALVE CARRYINGMEANS WHICH COOPERATES WITH THE WALL OF THE BORE TO THROTTLEPROGRESSIVELY SAID COMMUNICATION AS THE VALVE MOVES TOWARD THE FIRSTPOSITION; (E) SPRING MEANS BIASING THE FLOW CONTROL VALVE TOWARD THEFIRST POSTION; (F) MEANS DEFINING A DAMPING CHAMBER IN RESTRICTEDCOMMUNICATION WITH THE SECOND PASSAGES AND ENCLOSING ONE END OF THE FLOWCONTROL VAVLE; (G) MEANS AT THE OTHER END OF THE FLOW CONTROL VALVERESPONSIVE TO THE PRESSURE IN THE THIRD PASSAGE FOR URGING THE FLOWCONTROL VALVE TOWARD THE SECOND POSITION; (H) AN INTERNAL PASSAGE IN THEFLOW CONTROL VALVE INTERSECTED BY FIRST AND SECOND LONGITUDINALLY SPACEDTRANSVERSE PASSAGES THAT OPEN THROUGH THE OUTER PERIPHERY OF THE FLOWCONTROL VALVE AND REGISTER WITH THE FIRST AND SECOND PASSAGES,RESPECTIVELY, WHEN THE FLOW CONTROL VALVE IS IN THE FIRST POSITION; (I)A FIRST CHECK VALVE LOCATED IN THE INTERNAL PASSAGE AND ARRANGED TOPREVENT FLOW FROM THE FIRST TRANSVERSE PASSAGE TO THE SECOND TRANSVERSEPASSAGE THROUGH THE INTERNAL PASSAGE BUT TO PERMIT FLOW IN THE REVERSEDIRECTION; (J) BIASING MEANS, INCLUDING MEANS RESPONSIVE TO THE PRESSUREIN THE FIRST PASSAGE AND A SPRING, URGING THE FIRST CHECK VALVE CLOSED;(K) A BY-PASS PASSAGE INTERCONNECTING THE FIRST AND THIRD PASSAGES; (L)A SECOND CHECK VALVE ARRANGED TO PREVENT FLOW FROM THE THIRD PASSAGE TOTHE BY-PASS PASSAGE BUT TO PERMIT FLOW IN THE REVERSE DIRECTION; (M) ACONTROL CHAMBER HAVING A RESTRICTED INLET CONNECTION LEADING TO THEPASSAGE AND AN OUTLET CONNECTION; (N) A BY-PASS VALVE CONTROLLINGCOMMUNICATION BETWEEN THE FIRST PASSAGE AND THE BY-PASS PASSAGE; (O)SPRING BIASING THE BY-PASS VALVE CLOSED; AND (P) MEANS RESPONSIVE TO THEPRESSURE DIFFERENTIAL BETWEEN THE FIRST PASSAGE AND THE CONTROL CHAMBERFOR MOVING THE BY-PASS VALVE IN THE OPENING DIRECTION.